Hi Michael,
Sorry to disturb you again. I am doing microbunching instability study in Linac with elegant. I have two questions about the LSC model in Elegant.
- Does elegant consider about the energy chirp effects to the whole beam?
Physically, the head should be accelerated due to LSC, the tail decelerated.
The following picture is a simple example with 1 meter lscdrift . Only energy modulation due to initial density modulation is seen. I tried increase the beam current and transfer distance, still can not see the chirp effects.
- I want to consider about the LSC in Linac, but keep Linearize=1, which will need to keep N_KICKS=1 to consider LSC. So I divide the cavity to many parts and make sure the single cavity length is small enough. Is this method valid ?
The example file is attached. The input.sdds file seems too large, which is generated using matlab to introduce the density modulation.
Best,
Biaobin
Simulation of LSC in drift and Linac
Moderators: cyao, michael_borland
Simulation of LSC in drift and Linac
- Attachments
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- LSC_Cavity_Drift.zip
- (23.56 MiB) Downloaded 232 times
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- w1.png (6.41 KiB) Viewed 4191 times
Re: Simulation of LSC in drift and Linac
Hello,
When I am tracking particles with a linac, the following lattice layout of line0 and line1 will give different energy chirp calculated from the final particles distribution,
but R65 in the total transfer matrix of *.mpr file shows the same result in both lines. I can't understand the reasons causing
the differences. Is there a method to make the energy chirp of tracking results with LINE0 same with R65 in *.mpr ?
The elegant files and matlab scripts to get the chirp are attached.
Thanks in advance.
Biaobin
When I am tracking particles with a linac, the following lattice layout of line0 and line1 will give different energy chirp calculated from the final particles distribution,
Code: Select all
W0: WATCH,FILENAME="W0.out",MODE="COORD"
W1: WATCH,FILENAME="W1.out",MODE="COORD"
CAV0: RFCA,L=15,VOLT="1.553178354259261e+10",PHASE=0.069167595843681,&
FREQ=1e6,CHANGE_P0=1,END1_FOCUS=1,END2_FOCUS=1,LINEARIZE=0,fiducial=first
!8*CAV0 as a whole linac
CAV1: RFCA,L="15 8 *",VOLT="1.553178354259261e+10 8 *",PHASE=0.069167595843681,&
FREQ=1e6,CHANGE_P0=1,END1_FOCUS=1,END2_FOCUS=1,LINEARIZE=0,fiducial=first
! using separate cavity
! By particle tracking, the final energy chirp is 10.4517, R65=10.4167 in *.mpr file
! ---------------------
LINE0: LINE=(W0,8*CAV0,W1)
! using a whole cavity
! Particle tracking agree with *.mpr's R65, both are 10.4167, agree with the linear
! theory calculation of energy chirp as: h= ( delta_U * cot(phi) * 2 *pi*f/c ) / (U_0 + delta_U)
! ---------------------
LINE1: LINE=(W0,CAV1,W1)
but R65 in the total transfer matrix of *.mpr file shows the same result in both lines. I can't understand the reasons causing
the differences. Is there a method to make the energy chirp of tracking results with LINE0 same with R65 in *.mpr ?
The elegant files and matlab scripts to get the chirp are attached.
Thanks in advance.
Biaobin
- Attachments
-
- Linac_chirp.zip
- (13.85 KiB) Downloaded 223 times